SHIGELLA

Shigella

1. Definition: Shigella is a genus of Gram-negative, non-motile, non-spore forming, rod-shaped bacteria that cause shigellosis, a form of dysentery.
2. Causes: Shigella is spread through contaminated food and water, poor hygiene, and close contact with an infected person.
3. Types: a. Shigella dysenteriae (Shiga toxin-producing Shigella) b. Shigella flexneri c. Shigella boydii d. Shigella sonnei

Pathogenesis

1. → Shigella enters the body through consumption of contaminated food or water.
2. → Shigella adheres to the intestinal epithelial cells.
3. → Shigella invades the epithelial cells.
4. → Shigella multiplies and produces toxins.
5. → Toxins cause inflammation and damage to the intestinal mucosa.
6. → Inflammation and damage lead to diarrhea, abdominal pain, and other symptoms.

Morphology

1. Shigella is a Gram-negative, non-motile, non-spore forming, rod-shaped bacteria.
2. Shigella is approximately 2-3 μm in length and 0.5-1 μm in width.

Clinical Features

1. Diarrhea (often bloody)
2. Abdominal pain
3. Fever
4. Headache
5. Vomiting
6. Malabsorption of nutrients
7. Dehydration
8. Weight loss
9. Malnutrition

Complications

1. Dehydration and electrolyte imbalance
2. Malnutrition and weight loss
3. Intestinal obstruction
4. Abscesses
5. Perforation of the intestine
6. Sepsis
7. Meningitis
8. Encephalitis

Laboratory Diagnosis

1. Stool culture: Shigella can be isolated from stool specimens.
2. Shiga toxin detection: Shiga toxin can be detected in stool specimens using ELISA or PCR.
3. Antibody detection: Antibodies to Shigella can be detected in serum using ELISA or RIA.
4. PCR: PCR can be used to detect Shigella DNA in stool specimens.
5. Endoscopy: Endoscopy can be used to visualize the intestinal mucosa and collect biopsy specimens.

Memory Trick

• "Shigella Shiga" - Shigella produces Shiga toxin, which causes damage to the intestinal mucosa.
• "Shigella sonnei" - Shigella sonnei is the most common type of Shigella, which causes shigellosis.

Management

1. Fluid replacement: Fluid replacement is essential to prevent dehydration and electrolyte imbalance.
2. Rest: Rest is essential to allow the body to recover from the infection.
3. Antibiotics: Antibiotics may be prescribed to treat shigellosis, especially in severe cases.
4. Supportive care: Supportive care, such as nutrition and hydration, is essential to prevent malnutrition and weight loss.
5. Vaccination: Vaccination against Shigella can prevent shigellosis, especially in high-risk populations.